Communication method and device

Abstract

The invention relates to the technical field of communication, and discloses a communication method and device. The method comprises the following steps: receiving a random access request from a first terminal on a first cell, and determining that the random access request corresponds to a first random access or a second random access; under the condition that the random access request corresponds to the first random access, the TA of the first cell is sent to the first network equipment; under the condition that the random access request corresponds to second random access, the TA of the first cell is sent to the first terminal; wherein the first random access is the random access before switching, and the second random access is the random access after switching. By adopting the method, the random access (namely the first random access) before switching and the random access (namely the second random access) after switching can be supported at the same time, so that one random access can be flexibly executed according to actual requirements.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a communication method and device. Background Art

[0002] Cell switching is a very important feature in communication systems. It is mainly triggered by the movement of the terminal when the terminal is in a radio resource control (RRC) connection state, so that the terminal can be switched to a neighboring cell with better signal quality before the signal quality of the serving cell becomes incapable of communication, thereby providing continuous and uninterrupted communication services.

[0003] Taking the scenario where the terminal switches from cell 1 to cell 2 as an example, the terminal needs to obtain the timing advance (TA) of cell 2. For example, the terminal can obtain the TA of cell 2 through random access, and then send uplink information on cell 2 according to the TA of cell 2.

[0004] However, the implementation of obtaining TA through random access still needs further study. Summary of the invention

[0005] The present application provides a communication method and apparatus for simultaneously supporting random access before switching and random access after switching, so that one of the random accesses can be flexibly executed according to actual needs.

[0006] In a first aspect, an embodiment of the present application provides a communication method, which can be applied to a network device (such as a second DU, the second DU is a candidate DU or a target DU) or a module in the network device (such as a chip or a circuit). Taking the application of the method to the second DU as an example, in the method, the second DU receives a random access request from a first terminal on a first cell; determines whether the random access request corresponds to a first random access or a second random access; when the random access request corresponds to the first random access, sends a timing advance TA of the first cell to the first network device; when the random access request corresponds to the second random access, sends the TA to the first terminal; wherein the first random access is a random access before switching, and the second random access is a random access after switching.

[0007] By adopting the above method, after the second DU receives the random access request from the first terminal on the first cell, it can determine which type of random access the random access request corresponds to and perform corresponding operations, thereby simultaneously supporting the random access before switching (i.e., the first random access) and the random access after switching (i.e., the second random access), so as to flexibly execute one of the random accesses according to actual needs.

[0008] In one possible design, determining whether the random access request corresponds to the first random access or the second random access includes: if the random access resource corresponding to the random access request is the first random access resource, determining that the random access request corresponds to the first random access; if the random access resource corresponding to the random access request is the second random access resource, determining that the random access request corresponds to the second random access.

[0009] In this way, the first random access and the second random access can correspond to different random access resources, so that after receiving the random access request, the second DU can determine whether the random access request corresponds to the first random access or the second random access according to the random access resource corresponding to the random access request, which is more convenient to implement.

[0010] In one possible design, the method also includes: sending a first message to the first network device, the first message being used to indicate that the first random access resource corresponds to the first random access and the second random access resource corresponds to the second random access.

[0011] In one possible design, the method also includes: receiving a first request message from the first network device, the first request message being used to request allocation of random access resources corresponding to the first random access and random access resources corresponding to the second random access.

[0012] In this way, the second DU can allocate random access resources corresponding to the first random access and random access resources corresponding to the second random access based on the request of the first network device (such as CU), which facilitates flexible management and control of the CU.

[0013] In a possible design, the first random access is a non-contention-based random access; the first random access resources are used for multiple terminals to perform the first random access, and source network devices of the multiple terminals are all second network devices.

[0014] In this way, since the first random access resource corresponding to the first random access can be shared by multiple terminals under the second network device (such as the first DU), the first DU can flexibly allocate the first random access resource to the corresponding terminal for use, thereby improving the utilization rate of the random access resource, allowing more terminals to initiate the first random access and reduce the switching delay.

[0015] In one possible design, the second random access is a non-contention-based random access; the second random access resource is used for multiple terminals to perform the second random access, and the source network devices of the multiple terminals are all second network devices; in this way, the first DU can flexibly allocate the first random access resource to the corresponding terminal for use, so as to improve the utilization rate of the random access resource. Alternatively, the second random access resource is dedicated to the first terminal; in this way, it is easy to improve the success rate of the second random access.

[0016] In one possible design, the method also includes: receiving first indication information from a second network device; and determining, based on the first indication information, whether the random access request corresponds to the first random access or the second random access.

[0017] In this way, the second DU can determine which type of random access the random access request corresponds to based on the first indication information of the second network device (such as the first DU), which facilitates flexible management and control of the first DU.

[0018] In one possible design, the random access request corresponds to a third random access resource; and according to the first indication information, determining that the random access request corresponds to the first random access or the second random access includes: if the first indication information indicates that the third random access resource corresponds to the first random access, determining that the random access request corresponds to the first random access; if the first indication information indicates that the third random access resource corresponds to the second random access, determining that the random access request corresponds to the second random access.

[0019] In one possible design, the method also includes: sending a second message to the first network device, the second message being used to indicate that the third random access resource corresponds to the first random access and the second random access.

[0020] In one possible design, the method also includes: receiving a second request message from the first network device, the second request message being used to request allocation of random access resources corresponding to the first random access and the second random access.

[0021] In one possible design, the first random access and the second random access are both non-contention-based random access; the third random access resource is used for multiple terminals to perform the first random access and the second random access, and the source network devices of the multiple terminals are all second network devices.

[0022] In one possible design, sending the TA to the first terminal includes: receiving second indication information from a second network device, the second indication information is used to indicate beam information of the first cell; and sending a random access response to the first terminal according to the beam information, the random access response including the TA.

[0023] In this way, the second DU can send a random access response to the first terminal according to the beam information of the first cell, so as to facilitate the first terminal to receive the random access response and improve the success rate of random access.

[0024] In a second aspect, an embodiment of the present application provides a communication method, which can be applied to a network device (such as a source DU) or a module in the network device (such as a chip or a circuit). Taking the application of the method to a network device as an example, in the method, the network device receives a third message from a first network device, where the third message is used to indicate that the first random access resource corresponds to the first random access and the second random access resource corresponds to the second random access; if it is determined that the first terminal needs to initiate the first random access, a third indication information is sent to the first terminal, where the third indication information is used to instruct the first terminal to use the first random access resource to send a first random access request on the first cell; if it is determined that the first terminal needs to initiate the second random access, a fourth indication information is sent to the first terminal, where the fourth indication information is used to instruct the first terminal to use the second random access resource to send a second random access request on the first cell; wherein the first random access is a random access before switching, and the second random access is a random access after switching.

[0025] In one possible design, if it is determined that the first terminal needs to initiate the first random access, the method also includes: receiving the TA of the first cell from a third network device; sending a switching command to the first terminal, the switching command being used to indicate that the first cell is a target cell, and the switching command including the TA.

[0026] In one possible design, if it is determined that the first terminal needs to initiate the second random access, the method also includes: sending second indication information to a third network device, the second indication information is used to indicate the beam information of the first cell, and the beam information is used by the third network device to send the TA of the first cell to the first terminal.

[0027] In one possible design, if it is determined that the first terminal needs to initiate the second random access, the method also includes: sending fifth indication information to the first terminal, the fifth indication information is used to indicate the beam information of the first cell, and the beam information is used by the first terminal to receive the TA of the first cell.

[0028] In a possible design, the first random access is a non-contention-based random access; the first random access resources are used for multiple terminals to perform the first random access, and source network devices of the multiple terminals are all second network devices.

[0029] In one possible design, the second random access is a non-contention-based random access; the second random access resources are used for multiple terminals to perform the second random access, and the source network devices of the multiple terminals are all second network devices; or, the second random access resources are dedicated to the first terminal.

[0030] In a third aspect, an embodiment of the present application provides a communication method, which can be applied to a network device (such as a source DU) or a module in the network device (such as a chip or a circuit). Taking the application of the method to a network device as an example, in the method, the network device receives a fourth message from a second network device, and the fourth message is used to indicate that the third random access resource corresponds to the first random access and the second random access; if it is determined that the first terminal needs to initiate the first random access, a third indication information is sent to the first terminal, and the third indication information is used to instruct the first terminal to use the third random access resource to send a first random access request on the first cell; if it is determined that the first terminal needs to initiate the second random access, a fourth indication information is sent to the first terminal, and the fourth indication information is used to instruct the first terminal to use the third random access resource to send a second random access request on the first cell; wherein the first random access is a random access before switching, and the second random access is a random access after switching.

[0031] In one possible design, if it is determined that the first terminal needs to initiate the first random access, the method also includes: receiving the TA of the first cell from a third network device; sending a switching command to the first terminal, the switching command being used to indicate that the first cell is a target cell, and the switching command including the TA.

[0032] In one possible design, the method also includes: sending first indication information to a third network device; wherein, if it is determined that the first terminal is required to initiate the first random access, the first indication information is used to indicate that the third random access resource corresponds to the first random access; if it is determined that the first terminal is required to initiate the second random access, the first indication information is used to indicate that the third random access resource corresponds to the second random access.

[0033] In one possible design, if it is determined that the first terminal needs to initiate the second random access, the method also includes: sending second indication information to a third network device, the second indication information is used to indicate the beam information of the first cell, and the beam information is used by the third network device to send the TA of the first cell to the first terminal.

[0034] In one possible design, if it is determined that the first terminal needs to initiate the second random access, the method also includes: sending fifth indication information to the first terminal, the fifth indication information is used to indicate the beam information of the first cell, and the beam information is used by the first terminal to receive the TA of the first cell.

[0035] In one possible design, the first random access and the second random access are both non-contention-based random access; the third random access resource is used for multiple terminals to perform the first random access and the second random access, and the source network devices of the multiple terminals are all second network devices.

[0036] It can be understood that the method for which protection is sought in the second or third aspect corresponds to the first aspect, and the beneficial effects of the relevant technical features in the second or third aspect can be referred to the description of the first aspect and will not be repeated here.

[0037] In a fourth aspect, the present application provides a communication device, which has the function of implementing the functions involved in the first to third aspects above. For example, the communication device includes modules or units or means corresponding to the operations involved in the first to third aspects above. The functions or units or means can be implemented by software, or by hardware, or the corresponding software can be implemented by hardware.

[0038] In a possible design, the communication device includes a processing unit and a communication unit, wherein the communication unit can be used to send and receive signals to achieve communication between the communication device and other devices, for example, the communication unit is used to send system information to a terminal; the processing unit can be used to perform some internal operations of the communication device. The functions performed by the processing unit and the communication unit can correspond to the operations involved in the first to third aspects above.

[0039] In one possible design, the communication device includes a processor, which can be used to couple with a memory. The memory can store necessary computer programs or instructions for implementing the functions involved in the first to third aspects above. The processor can execute the computer program or instructions stored in the memory, and when the computer program or instructions are executed, the communication device implements the method in any possible design or implementation of the first to third aspects above.

[0040] In one possible design, the communication device includes a processor and a memory, and the memory can store necessary computer programs or instructions for implementing the functions involved in the first to third aspects. The processor can execute the computer program or instructions stored in the memory, and when the computer program or instructions are executed, the communication device implements the method in any possible design or implementation of the first to third aspects.

[0041] In one possible design, the communication device includes a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and execute the method in any possible design or implementation of the first to third aspects above.

[0042] It can be understood that in the fourth aspect above, the processor can be implemented by hardware or by software. When implemented by hardware, the processor can be a logic circuit, an integrated circuit, etc.; when implemented by software, the processor can be a general-purpose processor, which is implemented by reading the software code stored in the memory. In addition, the above processors can be one or more, and the memories can be one or more. The memory can be integrated with the processor, or the memory can be separately set from the processor. In the specific implementation process, the memory can be integrated with the processor on the same chip, or can be set on different chips respectively. The embodiment of the present application does not limit the type of memory and the setting method of the memory and the processor.

[0043] In a fifth aspect, the present application provides a communication system, which may include a first communication device and a second communication device; wherein the first communication device is used to execute the method described in the first aspect above, and the second communication device is used to execute the method described in the second aspect and / or the third aspect above.

[0044] In a sixth aspect, the present application provides a computer-readable storage medium, in which computer-readable instructions are stored. When a computer reads and executes the computer-readable instructions, the computer executes a method in any possible design of the first to third aspects above.

[0045] In a seventh aspect, the present application provides a computer program product. When a computer reads and executes the computer program product, the computer executes the method in any possible design of the first to third aspects above.

[0046] In an eighth aspect, the present application provides a chip, comprising a processor, wherein the processor is coupled to a memory and is used to read and execute a software program stored in the memory to implement a method in any possible design of the first to third aspects above. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic diagram of the architecture of a communication system applicable to an embodiment of the present application;

[0048] Figure 2A A schematic diagram of a random access process provided in an embodiment of the present application;

[0049] Figure 2B A schematic diagram of another random access process provided in an embodiment of the present application;

[0050] Figure 3 A schematic diagram of a first random access process according to an embodiment of the present application;

[0051] Figure 4 A schematic diagram of a related process of second random access provided in an embodiment of the present application;

[0052] Figure 5 A flow chart corresponding to the communication method provided in Example 1 of the present application;

[0053] Figure 6 A flow chart corresponding to the communication method provided in Embodiment 2 of the present application;

[0054] Figure 7 A possible exemplary block diagram of a device involved in an embodiment of the present application;

[0055] Figure 8 A schematic diagram of the structure of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings in the embodiments of the present application. The technical solutions in the embodiments of the present application can be applied to various communication systems, such as universal mobile telecommunications system (UMTS), wireless local area network (WLAN), wireless fidelity (Wi-Fi) system, 4th generation (4G) mobile communication system, such as long term evolution (LTE) system, fifth generation (5G) mobile communication system, such as new radio (NR) system, and future evolved communication systems, such as sixth generation (6G) mobile communication system, etc.

[0057] The present application will present various aspects, embodiments or features around a system that may include multiple devices, components, modules, etc. It should be understood and appreciated that each system may include additional devices, components, modules, etc., and / or may not include all the devices, components, modules, etc. discussed in conjunction with the drawings. In addition, combinations of these schemes may also be used. In addition, in the embodiments of the present application, words such as "exemplarily" and "for example" are used to represent examples, illustrations or descriptions. Any embodiment or design described as an "example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present concepts in a specific way. In the embodiments of the present application, "of", "corresponding, relevant" and "corresponding" can sometimes be used interchangeably. It should be noted that when the distinction is not emphasized, the meanings to be expressed are consistent.

[0058] To facilitate understanding of the embodiments of the present application, first Figure 1 The communication system shown in the figure is used as an example to describe in detail the communication system applicable to the embodiment of the present application. Figure 1 As shown, the communication system 10 includes one or more network devices 20, and one or more terminals 30. Among them, the interface between the network device and the terminal can be a Uu interface (or called an air interface), and data can be transmitted between the network device 20 and the terminal 30 through air interface resources. Exemplarily, the terminal can be located within the communication coverage of one or more cells of the network device, and the cell providing service to the terminal (i.e., the service cell of the terminal) can be one or more. When there are multiple service cells of the terminal, the terminal can work according to one or more transmission technologies such as carrier aggregation (CA), dual connectivity (DC), coordinated multipoint (CoMP) transmission, and multiple transmission and reception point (mTRP).

[0059] (1) Terminal

[0060] The terminal can be a device that accesses the above communication system and has wireless transceiver functions. The terminal can also be called user equipment (UE), terminal equipment, user device, access terminal, user unit, user station, mobile station, mobile station (MS), remote station, remote terminal, mobile device, user terminal, terminal unit, terminal station, terminal device, wireless communication equipment, user agent or user device.

[0061] For example, the terminal in the embodiment of the present application can be a mobile phone, a personal digital assistant (PDA), a laptop computer, a tablet computer (Pad), a drone, a computer with wireless transceiver function, a machine type communication (MTC) terminal, a virtual reality (VR) terminal, an augmented reality (AR) terminal, an Internet of Things (IoT) terminal, a wireless terminal in industrial control, a wireless terminal in self driving, a wireless terminal in remote medical, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home (such as a game console, a smart TV, a smart speaker, a smart refrigerator, and fitness equipment, etc.), a vehicle-mounted terminal, and an RSU with terminal function.

[0062] (2) Network equipment

[0063] The network device is a device located at the network side of the above communication system and has wireless transceiver functions.

[0064] For example, the network device in the embodiment of the present application can be an access point (AP) in a Wi-Fi system, such as a home gateway, a router, a server, a switch, a bridge, etc., a base station, an evolved Node B (eNB), a radio network controller (RNC), a base station controller (BSC), a base transceiver station (BTS), a home base station, a baseband unit (BBU), a wireless relay node, a wireless backhaul node, a transmission point (TRP; or TP), etc., and can also be a next-generation base station (next generation NodeB, gNB) in a 5G system, or a network node constituting a gNB, such as a centralized unit (CU), a distributed unit (DU), a road side unit (RSU) with a base station function, etc., or can also be a satellite or various future forms of base stations.

[0065] (3) Communication between terminals and network devices

[0066] The communication between the terminal and the network device follows a certain protocol layer structure. For example, the control plane protocol layer structure may include the RRC layer, the packet data convergence protocol (PDCP) layer, the radio link control (RLC) layer, the media access control (MAC) layer and the physical layer (PHY); the user plane protocol layer structure may include the PDCP layer, the RLC layer, the MAC layer and the physical layer. In a possible implementation, the service data adaptation protocol (SDAP) layer may also be included above the PDCP layer. Among them, the SDAP layer, the PDCP layer, the RLC layer, the MAC layer and the physical layer may also be collectively referred to as the access layer. For a detailed description of each of the above protocol layers, please refer to the relevant technical specifications of the 3rd Generation Partnership Project (3GPP).

[0067] Taking downlink data transmission as an example, downlink data can be encapsulated in each layer of the network device. The data received by a layer from the upper layer of the layer is regarded as the service data unit (SDU) of the layer. After layer encapsulation, it becomes a protocol data unit (PDU) and is passed to the next layer. For example, the data received by the PDCP layer entity from the SDAP layer can be called PDCP SDU. After the PDCP layer entity encapsulates the PDCP SDU, it obtains the PDCP PDU and sends it to the RLC layer; the PDCP PDU received by the RLC layer entity from the PDCP layer can be called RLC SDU. After the RLC layer entity encapsulates the RLC SDU, it obtains the RLC PDU and sends it to the MAC layer.

[0068] From the perspective of the terminal, after the physical layer of the terminal receives the transmission block from the network device, it can be delivered from the physical layer to the upper layer in sequence, and the corresponding decapsulation can be performed in each layer. In other words, the processing performed by each layer in the terminal can be the reverse process of the processing performed by each layer in the network device.

[0069] (4) CU-DU separation architecture

[0070] For example, in some possible network structures, the network device may include one or more centralized units (CU) and / or one or more distributed units (DU), and multiple DUs may be centrally controlled by one CU, and this architecture may be referred to as a CU-DU separation architecture. As an example, the interface between the CU and the DU may be referred to as an F1 interface, wherein the control plane (CP) interface may be an F1-C interface, and the user plane (UP) interface may be an F1-U interface.

[0071] The processing functions of CU and DU can be divided according to the protocol layer of the wireless network: for example Figure 2A As shown, the functions of the PDCP layer and the protocol layers above are set in the CU, and the functions of the protocol layers below the PDCP layer (such as the RLC layer and the MAC layer, etc.) are set in the DU. It can be understood that the above-mentioned division of the processing functions of the CU and DU according to the protocol layer is only an example, and can also be divided in other ways, such as the functions of the protocol layers above the RLC layer are set in the CU, and the functions of the protocol layers below the RLC layer are set in the DU. For example, the CU or DU can be divided into functions with more protocol layers, and for example, the CU or DU can also be divided into partial processing functions with protocol layers. The embodiments of the present application are not limited to this.

[0072] Furthermore, the functions of CU can be implemented by one entity, or by different entities. For example, the functions of CU can be further divided, that is, the control plane and the user plane are separated and implemented through different entities, namely the control plane CU entity (i.e., CU-CP entity) and the user plane CU entity (i.e., CU-UP entity). The CU-CP entity and the CU-UP entity can be coupled with the DU to jointly complete the functions of the RAN device. The interface between the CU-CP entity and the CU-UP entity can be an E1 interface, the interface between the CU-CP entity and the DU can be an F1-C interface, and the interface between the CU-UP entity and the DU can be an F1-U interface. Among them, a DU and a CU-UP can be connected to a CU-CP. Under the control of the same CU-CP, a DU can be connected to multiple CU-UPs, a CU-UP can be connected to multiple DUs, and under the collaboration of multiple CU-CPs, a CU-UP can also be connected to multiple collaborative CU-CPs, thereby improving the elasticity of the CU-CP. Figure 2B Figure 1 is a schematic diagram of the air interface protocol stack distribution. Figure 2B As shown, for both the user plane and the control plane, the air interface protocol stack can be RLC, MAC, PHY in DU, and PDCP and above protocol layers in CU.

[0073] It is understandable that in the above Figure 2A and Figure 2B In the illustrated architecture, the signaling generated by the CU can be sent to the terminal through the DU, or the signaling generated by the terminal can be sent to the CU through the DU. The DU may not parse the signaling but directly encapsulate it through the protocol layer and transparently transmit it to the terminal or CU. In the following embodiments, if the transmission of such signaling between the DU and the terminal is involved, then the sending or receiving of the signaling by the DU includes this scenario. For example, the signaling of the RRC or PDCP layer will eventually be processed into physical layer data and sent to the terminal, or converted from the received physical layer data. Under this architecture, the signaling of the RRC layer or PDCP layer can also be considered to be sent by the DU, or by the DU and the radio frequency device.

[0074] The communication system and business scenarios described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. A person of ordinary skill in the art can appreciate that with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0075] The relevant technical features involved in the embodiments of the present application are first explained below. These explanations are intended to make the embodiments of the present application easier to understand and should not be regarded as limiting the scope of protection claimed for the present application.

[0076] 1. Cell switching

[0077] Cell handover can be divided into two types, one of which is cell handover based on layer 1 / layer 2, which can be called layer 1 / layer 2 handover or layer 1 / layer 2 triggered mobility (L1 / L2 triggered mobility, LTM), and the other is cell handover based on layer 3, which can be called layer 3 handover (L3 handover). Layer 1 can refer to the physical layer, layer 2 can refer to any one or more layers of the MAC layer, RLC layer, PDCP layer, and SDAP layer, and layer 3 can refer to the RRC layer. It can be understood that layer 1 / layer 2 handover can also be understood as layer 1 and / or layer 2 handover; when it is an "and" relationship, the operations related to the handover process are mainly completed by layer 1 and layer 2; when it is an "or" relationship, the operations related to the handover process are mainly completed by layer 1 or layer 2. Since layer 1 and layer 2 are located at a lower level of the protocol stack than the RRC layer (layer 3), layer 1 / layer 2 handover can also be called low-layer handover, or bottom layer handover, or lower layer handover.

[0078] For layer 3 switching, in the CU-DU separation architecture, the CU receives the measurement results of the terminal (the measurement results are forwarded to the CU by the DU), and determines whether to initiate switching based on the measurement results. If it is determined to initiate switching, the switching command is sent to the DU, and the DU sends it to the terminal. Since this process involves communication interaction between the CU and DU (i.e., the interaction of the F1 interface), and the maximum transmission delay of the F1 interface is about 3ms to 10ms, it will cause a certain switching delay.

[0079] The switching decision of layer 1 / layer 2 switching is delegated from CU to DU. That is, DU determines whether to initiate switching (LTM cell switch) based on the measurement results of the terminal and sends the switching command directly to the terminal, which can effectively reduce F1 interaction and reduce switching latency.

[0080] 2. Cell switching scenarios

[0081] As mentioned above, the network device may include one or more CUs and one or more DUs. For example, the network device includes a CU and multiple DUs, the multiple DUs may be centrally controlled by a CU, and each of the multiple DUs may include one or more cells. It is understandable that "DU includes one or more cells" may also be described as "DU manages or controls one or more cells", or "one or more cells of DU", or "one or more cells belong to DU".

[0082] When a terminal switches between different cells, there may be multiple specific switching scenarios. For example, the switching scenarios may be divided according to the location relationship between the source cell and the target cell. The location relationship between the source cell and the target cell may refer to whether the source cell and the target cell belong to the same DU. Two possible switching scenarios are described here, namely scenario 1 and scenario 2.

[0083] Scenario 1: The terminal switches from one cell of a DU to another cell of the DU, that is, the source cell and the target cell of the terminal belong to the same DU. The cell switching corresponding to scenario 1 is intra-DU switching.

[0084] Scenario 2: The terminal switches from a cell of DU1 controlled by a CU to a cell of DU2 controlled by the CU. At this time, DU1 can be called the source DU and DU2 can be called the target DU. In other words, the source cell and the target cell of the terminal belong to different DUs controlled by the same CU. The cell switching corresponding to scenario 2 is inter-DU switching.

[0085] The above-mentioned intra-DU switching and inter-DU switching can both be implemented through layer 1 / layer 2 switching. In the embodiment of the present application, inter-DU switching will be taken as an example for description.

[0086] 3. Random Access

[0087] Random access refers to the process from when a terminal sends a random access request to try to access the network to when a basic signaling connection is established with a network device. For example, a random access request may be a preamble of a random access. In the embodiment of the present application, random access may also be referred to as a random access process or a random access channel (RACH) process.

[0088] Depending on whether the preamble sent by the terminal is selected by the terminal itself, random access can be divided into contention based random access (CBRA) and contention free random access (CFRA). In contention based random access, the preamble can be selected by the terminal; in non-contention based random access, the preamble can be allocated to the terminal by the network device.

[0089] 4. First Random Access and Second Random Access

[0090] Taking the scenario where the terminal switches from cell 1 to cell 2 as an example, the terminal can obtain the TA of cell 2 by initiating a first random access, or can also initiate a second random access to obtain the TA of cell 2. The first random access is a random access before switching, which can be called early random access (referred to as early RACH); the second random access is a random access after switching, which can be called normal random access (referred to as normal RACH).

[0091] Here, the timing of switching is when the terminal receives the switching command, "before switching" can be understood as before the terminal receives the switching command, that is, the first random access is a random access initiated before the terminal receives the switching command (such as a switching command instructing the terminal to switch to cell 2), and "after switching" can be understood as after the terminal receives the switching command, that is, the second random access is a random access initiated after the terminal receives the switching command (such as a switching command instructing the terminal to switch to cell 2).

[0092] Combine the following Figure 3 , the relevant implementation process of the first random access is described. Figure 3 As shown, the process may include:

[0093] S301, the terminal sends a random access request to a candidate DU in one or more candidate cells (taking cell 2 as an example).

[0094] S302: After receiving the random access request, the candidate DU sends the TA of cell 2 to the source DU.

[0095] Here, the candidate DU may measure the TA of cell 2 according to the random access request and send the TA of cell 2 to the CU, and then the CU forwards the TA of cell 2 to the source DU.

[0096] S303, if the source DU determines to initiate LTM switching, it sends a switching command to the terminal, the switching command is used to instruct the terminal to switch to cell 2, and the switching command includes the TA of the target cell (ie, cell 2); accordingly, the terminal receives the switching command.

[0097] S304: The terminal sends uplink information in cell 2 according to the TA carried in the handover command.

[0098] The uplink information may be carried on a physical uplink control channel (physical uplink control channel, PUCCH) or a physical uplink shared channel (physical uplink shared channel, PUSCH).

[0099] In the above process, after the candidate DU receives the random access request, it is not necessary to send a random access response to the terminal; that is, after the terminal sends the random access request, it can be determined that the first random access is completed.

[0100] Combine the following Figure 4 , describes the relevant implementation process of the second random access. Figure 4 As shown, the process may include:

[0101] S401, the source DU determines to initiate an LTM handover and sends a handover command to the terminal, where the handover command is used to instruct the terminal to switch to cell 2; accordingly, the terminal receives the handover command.

[0102] S402: The terminal sends a random access request to the target DU in the target cell (ie, cell 2) according to the handover command.

[0103] S403, the target DU sends a random access response to the terminal according to the random access request, where the random access response includes the TA of cell 2; accordingly, the terminal receives the random access response.

[0104] S404: The terminal sends uplink information in cell 2 according to the TA carried in the random access response.

[0105] It is understandable that the above Figure 3 and Figure 4 These are just two possible process examples. The specific implementation may also include other possible steps, which are not specifically limited.

[0106] According to the description of the above-mentioned related technical features, it can be known that the terminal can initiate the first random access or the second random access to obtain the TA of the target cell.

[0107] However, existing communication systems usually only support one type of random access, which makes the implementation inflexible.

[0108] Based on this, an embodiment of the present application provides a communication method for simultaneously supporting random access before switching and random access after switching, so that one of the random accesses can be flexibly executed according to actual needs.

[0109] The communication method provided in the embodiment of the present application is described in detail below in combination with Example 1 and Example 2. Among them, the communication method provided in the embodiment of the present application involves communication between multiple network devices (such as a first network device, a second network device, and a third network device) and a terminal. Unless otherwise specified, "terminal" may refer to the terminal itself or to a component in the terminal, such as a chip or a chip system; "network device" may refer to the network device itself or to a component in the network device, such as a chip or a chip system. The following description will be taken as an example of "the first network device is a CU, the second network device is a first DU managed by the CU, and the third network device is a second DU managed by the CU".

[0110] Embodiment 1

[0111] Figure 5 This is a flow chart corresponding to the communication method provided in Example 1 of the present application, such as Figure 5 As shown, the method includes:

[0112] S501, the CU sends a first request message to the second DU, where the first request message is used to request allocation of random access resources corresponding to a first random access and random access resources corresponding to a second random access.

[0113] Here, after the CU decides to initiate the LTM configuration process for the first terminal, it can send a first request message to the DU to which one or more candidate cells belong. Among them, the source DU of the switch is the first DU. For example, one or more candidate cells include a first cell, and the DU to which the first cell belongs is the second DU (that is, the second DU is the candidate DU of the first terminal). In the embodiment of the present application, the first cell among multiple candidate cells will be taken as an example. The first request message sent by the CU to the second DU can be used to request the second DU to allocate random access resources corresponding to the first random access and / or random access resources corresponding to the second random access on the first cell, and other candidate cells can be processed accordingly.

[0114] Exemplarily, the first request message may be a UE context setup request message. The first request message may include request information a and request information b, request information a is used to request allocation of random access resources corresponding to the first random access, and request information b is used to request allocation of random access resources corresponding to the second random access; that is, different (separate) request information may be used to request random access resources corresponding to different random accesses. Alternatively, the first request message may include request information c, request information c is used to request allocation of random access resources corresponding to the first random access and random access resources corresponding to the second random access; that is, the same request information may be used to request random access resources corresponding to different random accesses.

[0115] Exemplarily, the first request message may include information for identifying the first DU. The information for identifying the first DU may include at least one of the following: an identifier of the first DU; an identifier of a source cell of the first terminal; an index value, the index value being associated with the first DU and / or the source cell. For example, the index value may be generated by the CU for the first DU and / or the source cell.

[0116] Exemplarily, the first random access may be a non-contention random access, and the second random access may be a contention random access or a non-contention random access. In the embodiment of the present application, description will be made by taking "both the first random access and the second random access are non-contention random access" as an example.

[0117] S502, the second DU sends a first message to the CU, where the first message is used to indicate that the first random access resource corresponds to the first random access and the second random access resource corresponds to the second random access; accordingly, the CU receives the first message.

[0118] Here, the second DU allocates the first random access resources corresponding to the first random access and the second random access resources corresponding to the second random access on the first cell according to the first request message (that is, the first random access resources and the second random access resources are random access resources belonging to the first cell), and sends the first message to the CU.

[0119] (1) Describe the first message.

[0120] Exemplarily, the first message may be a UE context setup response message. There are multiple indication modes of "the first message indicates that the first random access resource corresponds to the first random access and the second random access resource corresponds to the second random access", such as indication mode 1 and indication mode 2.

[0121] Indication method 1: The first message may include a first field corresponding to the first random access and a second field corresponding to the second random access. The first field includes first resource information, and the first resource information is used to indicate the first random access resource; the second field includes second resource information, and the second resource information is used to indicate the second random access resource. In other words, the correspondence between the random access resource and the random access is indicated by carrying the first resource information and the second resource information in specific fields respectively.

[0122] Indication method 2: The first message includes first resource information and indication information a, as well as second resource information and indication information b. Indication information a is used to indicate that the random access resource indicated by the first resource information (i.e., the first random access resource) corresponds to the first random access, and indication information b is used to indicate that the random access resource indicated by the second resource information (i.e., the second random access resource) corresponds to the second random access. In other words, the correspondence between the random access resource and the random access is indicated by the additional indication information a and indication information b.

[0123] (2) Describe the first random access resource.

[0124] The first random access resource may include: an index of one or more preambles; and / or time-frequency resource information for carrying one or more preambles. For example, the first random access resource includes an index of a preamble and time-frequency resource information for carrying the preamble, or the first random access resource includes indexes of multiple preambles (such as {preamble 1, preamble 2, preamble 3}) and time-frequency resource information for carrying the multiple preambles.

[0125] Exemplarily, the first random access resource may be shared by multiple terminals, that is, the first random access resource is used for multiple terminals to perform the first random access, the multiple terminals include the first terminal, and the source DUs of the multiple terminals are all the first DU. For example, the first request message includes information for identifying the first DU, and then the second DU can allocate the same first random access resource to multiple terminals under the same source DU.

[0126] For example, the first random access resources allocated to the second DU according to the first request message include {preamble 1, preamble 2, preamble 3}; if the second DU also receives a request message sent by the CU to the second terminal, and the source DU of the second terminal is also the first DU, the first random access resources allocated to the second DU may also include {preamble 1, preamble 2, preamble 3}.

[0127] "Multiple terminals share the first random access resource" in the embodiment of the present application means that multiple terminals can use the first random access resource to initiate the first random access, and which random access resource in the first random access resource is used to initiate the first random access (for example, which preamble among preamble 1, preamble 2, and preamble 3) can be indicated by the source DU according to actual needs. For example, in the above example, the first random access resource includes {preamble 1, preamble 2, preamble 3}. If the first terminal and the second terminal perform the first random access at the same time, the source DU (i.e., the first DU) can allocate different preambles to the first terminal and the second terminal, such as allocating preamble 1 to the first terminal and allocating preamble 2 to the second terminal; if the first terminal and the second terminal perform the first random access successively (not at the same time), the first DU can allocate the same preamble to the first terminal and the second terminal. Other matters involving "sharing" can be handled with reference.

[0128] (3) Describe the second random access resource.

[0129] The second random access resource may include: an index of one or more preambles; and / or time-frequency resource information for carrying one or more preambles. For example, the second random access resource includes an index of a preamble and time-frequency resource information for carrying the preamble, or the second random access resource includes indexes of multiple preambles (such as {preamble 4, preamble 5, preamble 6}) and time-frequency resource information for carrying the multiple preambles. The second random access resource and the first random access resource may be different random access resources.

[0130] Exemplarily, the second DU may allocate a second random access resource for the first terminal. In this case, the second random access resource may be dedicated to the first terminal, that is, the second random access resource is used by the first terminal for the second random access. Alternatively, the second DU may also allocate a second random access resource for multiple terminals. In this case, the second random access resource may be shared by multiple terminals, that is, the second random access resource is used by multiple terminals for the second random access, the multiple terminals include the first terminal, and the source DUs of the multiple terminals are all the first DU. For details, please refer to the description of the first random access resource.

[0131] In addition, the first message may also include other possible information, such as an identifier of the first terminal in the first cell, where the identifier may be a cell radio network temporary identifier (C-RNTI).

[0132] It can be understood that the above S501 is an optional step, that is, the second DU can send the first message to the CU based on the first request message, or can also actively send the first message to the CU. S502 can also be an optional step. When the CU initiates the LTM configuration process for other terminals under the first DU, it has obtained the first random access resource and the second random access resource allocated by the second DU (shared by multiple terminals under the first DU), then S502 does not need to be executed.

[0133] S503: The CU sends a third message to the first DU, where the third message is used to indicate that the first random access resource corresponds to a first random access and the second random access resource corresponds to a second random access.

[0134] Here, after receiving the first message, the CU may send the relevant information (such as the first resource information and the second resource information) in the first message to the first DU through a third message. For example, the third message may be a UE context modification request message. The specific implementation of "the third message indicates that the first random access resource corresponds to the first random access and the second random access resource corresponds to the second random access" may refer to the above-mentioned first message and will not be described in detail.

[0135] Exemplarily, the CU may store relevant information of the first terminal, such as the source DU of the first terminal, the identifier of the first terminal in each cell (including the source cell and the candidate cell), etc. Then, after the CU receives the first message, it can determine that the source DU of the first terminal is the first DU based on the identifier of the first terminal in the first cell carried by the first message, and then send the third message to the first DU. In other words, when the second DU sends the first message, it may not perceive the first DU, but the CU identifies the first message and forwards the relevant information in the first message to the first DU.

[0136] Optionally, the third message may also include an RRC reconfiguration message, and the RRC reconfiguration message may include the root sequence of the first random access preamble (referred to as root sequence 1) and the root sequence of the second random access preamble (referred to as root sequence 2), and the root sequence 1 and the root sequence 2 may be the same, or may be different, and are not specifically limited. Accordingly, after the first DU receives the third message, the RRC reconfiguration message therein may be sent to the first terminal, and other information in the third message except the RRC reconfiguration message (such as the first resource information and the second resource information) does not need to be sent to the first terminal.

[0137] Furthermore, the above method further includes S504-a to S507-a (corresponding to the first random access), or S504-b to S506-b (corresponding to the second random access). That is, the first terminal may perform the first random access without performing the second random access; or, may perform the second random access without performing the first random access.

[0138] S504-a, if the first DU determines that the first terminal needs to initiate the first random access, it sends third indication information to the first terminal, where the third indication information is used to instruct the first terminal to initiate the first random access in the first cell; accordingly, the first terminal receives the third indication information.

[0139] Here, there are multiple implementations of the first DU determining whether the first terminal needs to initiate the first random access. One possible implementation is that the first random access resource is shared by multiple terminals, and the first DU can determine whether the first terminal needs to initiate the first random access based on the usage of the first random access resource. For example, if the first random access resource is sufficient, the first DU can determine that the first terminal needs to initiate the first random access.

[0140] Exemplarily, the third indication information is used to indicate that the first terminal uses the first random access resource to initiate the first random access. For example, the first random access resource may be a resource set (such as {preamble 1, preamble 2, preamble 3}), which includes multiple random access resources. In this case, the third indication information is used to further indicate the specific resource used by the first terminal to initiate the first random access. For example, the third indication information includes the index of preamble 1, that is, it indicates that the first terminal uses preamble 1 to initiate the first random access.

[0141] In addition, there are multiple ways for the first DU to send the third indication information to the first terminal. For example, the first DU can send a PDCCH order to the terminal, and the PDCCH order includes the third indication information.

[0142] S505-a, the first terminal sends a first random access request on the first cell according to the third indication information; accordingly, the second DU receives the first random access request.

[0143] Here, the first terminal may send a first random access request on the first cell using the first random access resource according to the third indication information. For example, if the third indication information includes the index of preamble 1, the first terminal may generate preamble 1 according to the root sequence of the preamble of the first random access, and send preamble 1 to the second DU on the first cell.

[0144] S506-a, the second DU determines that the first random access request corresponds to the first random access or the second random access, and when the first random access request corresponds to the first random access, sends the TA of the first cell to the first DU; accordingly, the first DU receives the TA of the first cell.

[0145] Exemplarily, the second DU may determine the TA of the first cell according to the first random access request. And, the second DU may determine whether the random access resource corresponding to the first random access request is the first random access resource or the second random access resource to determine whether the first random access request corresponds to the first random access or the second random access. Here, since the random access resource corresponding to the first random access request is the first random access resource, the second DU may determine that the first random access request corresponds to the first random access.

[0146] It can be understood that the second DU does not need to send a random access response to the first terminal.

[0147] Exemplarily, in the embodiment of the present application, the information transmitted between the first DU and the second DU can be forwarded by the CU, for example, the second DU can send the TA of the first cell to the first DU through the CU. Other matters involving the communication between the first DU and the second DU can be handled with reference to the above.

[0148] S507-a, the first DU sends a switching command to the first terminal, where the switching command is used to instruct the first terminal to switch to the first cell, and the switching command includes the TA of the first cell; accordingly, the first terminal receives the switching command.

[0149] Exemplarily, if the first DU determines to switch the first terminal to the first cell, it can determine whether the TA of the first cell has been obtained through the first random access. If so (that is, the above S504-a to S506-a have been executed), a switching command can be sent to the first terminal. The switching command may include an identifier of the first cell (used to indicate that the first cell is the target cell) and the TA of the first cell.

[0150] Subsequently, the first terminal may send uplink information on the first cell according to the TA carried in the switching command, and specific details may refer to the prior art.

[0151] S504-b, if the first DU determines that the first terminal needs to initiate a second random access, it sends fourth indication information to the first terminal, where the fourth indication information is used to instruct the first terminal to initiate a second random access in the first cell; accordingly, the first terminal receives the fourth indication information.

[0152] Exemplarily, if the first DU determines to switch the first terminal to the first cell, it can determine whether there is a valid TA of the first cell. If not (for example, the above S504-a to S506-a are not executed to obtain the TA of the first cell, or although the above S504-a to S506-a are executed to obtain the TA of the first cell, the TA is invalid due to reasons such as a long acquisition time), it is determined that the first terminal needs to initiate a second random access, and send a switching command to the first terminal. The switching command is used to instruct the first terminal to switch to the first cell. The switching command may include fourth indication information. It can be understood that here, the fourth indication information is carried in the switching command as an example. In other implementations, the fourth indication information may also be a separate message or signaling, which is not specifically limited.

[0153] Exemplarily, the fourth indication information is used to instruct the first terminal to use the second random access resource to initiate the second random access. As described above, the second random access resource can be a resource set (such as {preamble 4, preamble 5, preamble 6}), which includes multiple random access resources. In this case, the fourth indication information is used to further indicate the specific resource used by the first terminal to initiate the second random access. For example, the fourth indication information includes the index of preamble 4, that is, it indicates that the first terminal uses preamble 4 to initiate the second random access.

[0154] S505-b, the first terminal sends a second random access request on the first cell using the second random access resource according to the fourth indication information; accordingly, the second DU receives the second random access request.

[0155] For example, the fourth indication information includes the index of preamble 4, then the first terminal may generate preamble 4 according to the root sequence of the preamble of the second random access, and send preamble 4 to the second DU on the first cell.

[0156] S506-b, the second DU determines that the second random access request corresponds to the first random access or the second random access, and when the second random access request corresponds to the second random access, sends the TA of the first cell to the first terminal; accordingly, the first terminal receives the TA of the first cell.

[0157] Exemplarily, the second DU may determine the TA of the first cell according to the second random access request. And, the second DU may determine whether the random access resource corresponding to the second random access request is the first random access resource or the second random access resource to determine whether the second random access request corresponds to the first random access or the second random access. Here, since the random access resource corresponding to the second random access request is the second random access resource, the second DU may determine that the second random access request corresponds to the second random access.

[0158] Exemplarily, the first DU may also send second indication information to the second DU, and the second indication information is used to indicate the beam information of the target cell (i.e., the first cell); further, the second DU may send a random access response to the first terminal based on the beam information of the first cell, and the random access response includes the TA of the first cell. For example, the beam information of the first cell may include a synchronization signal and a physical broadcast channel (PBCH) block (SSB) and / or a transmission configuration indication state (TCIstate) corresponding to the second random access resource (such as the preamble 4 indicated by the fourth indication information). Taking the beam information of the first cell including the SSB corresponding to the second random access resource as an example, the second DU may send a random access response to the first terminal based on the SSB beam.

[0159] The first DU may also send fifth indication information to the first terminal, and the fifth indication information is used to indicate the beam information of the target cell (i.e., the first cell); further, the first terminal may receive a random access response based on the beam information of the first cell. Taking the example that the beam information of the first cell includes the SSB corresponding to the second random access resource, the first terminal may receive a random access response based on the SSB beam. The beam information of the target cell indicated by the second indication information is the same as the beam information of the target cell indicated by the fifth indication information.

[0160] Exemplarily, the fifth indication information may be carried in the switching command. The embodiment of the present application does not limit the order in which the first DU sends the second indication information and the switching command; for example, the first DU may first send the switching command and then send the second indication information; or may first send the second indication information and then send the switching command; or may send the second indication information and the switching command at the same time.

[0161] Subsequently, the first terminal may send uplink information on the first cell according to the TA of the first cell, and specific details may refer to the prior art.

[0162] In the above-mentioned embodiment 1, the second random access is described as a non-competitive random access. In other examples, the second random access in embodiment 1 may also be a competitive random access. In this case, the above-mentioned fourth indication information does not need to indicate the specific resources used by the first terminal to initiate the second random access, but the specific resources used to initiate the second random access can be selected by the first terminal itself. For the relevant implementation of the second random access, reference can be made to the prior art.

[0163] By adopting the above method, the random access before switching (ie, the first random access) and the random access after switching (ie, the second random access) can be supported simultaneously, so that one of the random accesses can be flexibly executed according to actual needs.

[0164] From the perspective of the first DU, since the first random access resource corresponding to the first random access can be shared by multiple terminals under the first DU, the first DU can flexibly allocate the first random access resource to the corresponding terminal for use, without reserving a dedicated random access resource for each terminal (for example, Figure 3 In the illustrated process, it is necessary to reserve a dedicated random access resource for each terminal, so as to improve the utilization rate of the random access resource, so that more terminals can initiate the first random access and reduce the switching delay; and for the terminal that has not initiated the first random access, the first DU instructs it to initiate the second random access, so as to ensure the normal switching of these terminals. In addition, the second random access resource can be terminal-specific, so as to improve the success rate of the second random access.

[0165] From the perspective of the second DU, since the second DU allocates different random access resources for the first random access and the second random access, after receiving the random access request, the second DU can judge whether the random access request corresponds to the first random access or the second random access according to the random access resources corresponding to the random access request, and perform corresponding operations, so as to ensure the normal switching of the terminal.

[0166] Embodiment 2

[0167] Figure 6 This is a flow chart corresponding to the communication method provided in Example 2 of the present application, such as Figure 6 As shown, the method includes:

[0168] S601, the CU sends a second request message to the second DU, where the second request message is used to request allocation of random access resources corresponding to the first random access and the second random access.

[0169] In the above-mentioned embodiment 1, the first random access and the second random access correspond to different random access resources, and the first request message is used to request the random access resource corresponding to the first random access and the random access resource corresponding to the second random access. In the embodiment 2, the first random access and the second random access correspond to the same random access resource. Except for this difference, S601 can refer to S501.

[0170] In the second embodiment, the first random access and the second random access may both be non-contention-based random access.

[0171] S602, the second DU sends a second message to the CU, where the second message is used to indicate that the third random access resource corresponds to the first random access and the second random access; accordingly, the CU receives the second message.

[0172] Exemplarily, the third random access resource may include: an index of one or more preambles; and / or time-frequency resource information for carrying one or more preambles. For example, the third random access resource includes an index of a preamble and time-frequency resource information for carrying the preamble, or the third random access resource includes indexes of multiple preambles (such as {preamble 1, preamble 2, preamble 3, preamble 4, preamble 5, preamble 6}) and time-frequency resource information for carrying the multiple preambles.

[0173] Exemplarily, the second DU can allocate a third random access resource for multiple terminals. In this case, the third random access resource can be shared by multiple terminals, that is, the third random access resource is used for multiple terminals to perform first random access and second random access. The multiple terminals include the first terminal, and the source DUs of the multiple terminals are all the first DU.

[0174] There are multiple ways for the second message to indicate that the third random access resource corresponds to the first random access and the second random access. For example, the second message includes a first field corresponding to the first random access and a second field corresponding to the second random access; both the first field and the second field include third resource information, and the third resource information is used to indicate the third random access resource. For another example, the second message includes a third field corresponding to the first random access and the second random access, and the third field includes third resource information. For another example, the second message may include third resource information and indication information c, and the indication information c is used to indicate that the third random access resource corresponds to the first random access and the second random access.

[0175] Exemplarily, other contents of the above S602 may refer to the description of S502 in the first embodiment. For example, similar to the first message, the second message may be a UE context establishment response message.

[0176] S603: The CU sends a fourth message to the first DU, where the fourth message is used to indicate that the third random access resource corresponds to the first random access and the second random access.

[0177] Furthermore, the above method further includes S604-a to S607-a (corresponding to the first random access), or S604-b to S606-b (corresponding to the second random access). That is, the first terminal may perform the first random access without performing the second random access; or, may perform the second random access without performing the first random access.

[0178] S604-a, if the first DU determines that the first terminal needs to initiate the first random access, it sends third indication information to the first terminal, where the third indication information is used to instruct the first terminal to initiate the first random access in the first cell; accordingly, the first terminal receives the third indication information.

[0179] Exemplarily, the third indication information is used to instruct the first terminal to use the third random access resource to initiate the first random access. As described above, the third random access resource can be a resource set (such as {preamble 1, preamble 2, preamble 3, preamble 4, preamble 5, preamble 6}), which includes multiple random access resources. In this case, the third indication information is used to further indicate the specific resource used by the first terminal to initiate the first random access. For example, the third indication information includes the index of preamble 1, that is, it indicates that the first terminal uses preamble 1 to initiate the first random access.

[0180] S605-a, the first terminal sends a first random access request on the first cell using the third random access resource according to the third indication information; accordingly, the second DU receives the first random access request.

[0181] S606-a, the first DU sends first indication information to the second DU; accordingly, the second DU determines, according to the first indication information, that the first random access request corresponds to the first random access.

[0182] Exemplarily, the first indication information is used to indicate that the third random access resource corresponds to the first random access or the second random access. For this step, for example, the third random access resource includes {preamble 1, preamble 2, preamble 3, preamble 4, preamble 5, preamble 6} and time-frequency resource information for carrying these preambles, then the first indication information is used to indicate that preamble 1 corresponds to the first random access; further, after the second DU receives the first random access request (i.e., preamble 1), it can be determined that the first random access request corresponds to the first random access. For example, the first indication information may include an identifier of the third random access resource (such as an index of preamble 1 and / or time-frequency resource information for carrying preamble 1).

[0183] Optionally, after receiving the first indication information, the second DU may send feedback information to the first DU.

[0184] It is understandable that if the first DU determines that the first terminal needs to initiate the first random access, the third indication information and the first indication information may be sent. The embodiment of the present application does not limit the order in which the first DU sends the third indication information and the first indication information. For example, it may be executed in the order of S604-a, S605-a, and S606-a, or it may be executed in the order of S606-a, S604-a, and S605-a, or S604-a and S606-a may be executed simultaneously, and then S605-a may be executed.

[0185] S607-a, the second DU sends the TA of the first cell to the first DU; correspondingly, the first DU receives the TA of the first cell.

[0186] S608-a, the first DU sends a switching command to the first terminal, where the switching command is used to instruct the first terminal to switch to the first cell, and the switching command includes the TA of the first cell; accordingly, the first terminal receives the switching command.

[0187] Exemplarily, if the first DU determines to switch the first terminal to the first cell, it can determine whether there is a valid TA of the first cell. If so (for example, by executing S604-a to S607-a above, the first DU obtains the TA of the first cell), a switching command can be sent to the first terminal. The switching command may include an identifier of the first cell (used to indicate that the first cell is the target cell) and the TA of the first cell.

[0188] Subsequently, the first terminal may send uplink information on the first cell according to the TA carried in the switching command, and specific details may refer to the prior art.

[0189] S604-b: If the first DU determines that the first terminal needs to initiate a second random access, it sends fourth indication information to the first terminal, where the fourth indication information is used to instruct the first terminal to initiate a second random access in the first cell.

[0190] Exemplarily, if the first DU determines to switch the first terminal to the first cell, it can determine whether there is a valid TA of the first cell. If not (for example, the above S604-a to S607-a are not executed to obtain the TA of the first cell, or although the above S604-a to S607-a are executed to obtain the TA of the first cell, the TA is invalid due to reasons such as a long acquisition time), it is determined that the first terminal needs to initiate a second random access and send a switching command to the first terminal. The switching command is used to instruct the first terminal to switch to the first cell. The switching command may include fourth indication information.

[0191] Exemplarily, the fourth indication information is used to instruct the first terminal to use the third random access resource to initiate the second random access. As described above, the third random access resource can be a resource set (such as {preamble 1, preamble 2, preamble 3, preamble 4, preamble 5, preamble 6}), which includes multiple random access resources. In this case, the fourth indication information is used to further indicate the specific resource used by the first terminal to initiate the second random access. For example, the fourth indication information includes the index of preamble 4, that is, it indicates that the first terminal uses preamble 4 to initiate the second random access.

[0192] S605-b, the first terminal sends a second random access request on the first cell according to the fourth indication information; accordingly, the second DU receives the second random access request.

[0193] S606-b, the first DU sends first indication information to the second DU; accordingly, the second DU determines, based on the first indication information, that the first random access request corresponds to the first random access.

[0194] Exemplarily, the first indication information is used to indicate that the third random access resource corresponds to the first random access or the second random access. For this step, for example, the third random access resource includes {preamble 1, preamble 2, preamble 3, preamble 4, preamble 5, preamble 6}, then the first indication information is used to indicate that preamble 4 corresponds to the second random access; further, after the second DU receives the second random access request (i.e., preamble 2), it can be determined that the second random access request corresponds to the second random access. For example, the first indication information may include an identifier of the third random access resource (such as an index of preamble 4 and / or time-frequency resource information for carrying preamble 4).

[0195] S607-b, the second DU sends a random access response to the first terminal, where the random access response includes the TA of the first cell.

[0196] Exemplarily, the first DU can also send second indication information to the second DU, and the second indication information is used to indicate the beam information of the target cell (i.e., the first cell); further, the second DU can send a random access response to the first terminal based on the beam information of the first cell, and the random access response includes the TA of the first cell.

[0197] The first DU may also send fifth indication information to the first terminal, and the fifth indication information is used to indicate the beam information of the target cell (i.e., the first cell); further, the first terminal may receive a random access response based on the beam information of the first cell, thereby facilitating improving the success rate of random access. For example, the fifth indication information may be carried in a handover command. The beam information of the target cell indicated by the second indication information is the same as the beam information of the target cell indicated by the fifth indication information.

[0198] For example, the beam information of the first cell may include the SSB and / or TCI state corresponding to the third random access resource (such as the preamble 4 indicated by the first indication information). Taking the beam information of the first cell including the SSB corresponding to the second random access resource as an example, the second DU may send a random access response to the first terminal according to the SSB beam. Accordingly, the first terminal may receive a random access response according to the SSB beam.

[0199] By adopting the above method, the random access before switching (ie, the first random access) and the random access after switching (ie, the second random access) can be supported simultaneously, so that one of the random accesses can be flexibly executed according to actual needs.

[0200] From the perspective of the first DU, since the third random access resource can be shared by multiple terminals under the first DU, the first DU can flexibly allocate the third random access resource to the corresponding terminal to initiate the first random access, without reserving a dedicated random access resource for each terminal (for example, Figure 3 In the process shown, it is necessary to reserve a dedicated random access resource for each terminal) to improve the utilization rate of the random access resources, so that more terminals can initiate the first random access and reduce the switching delay; and for the terminal that has not initiated the first random access, the first DU instructs it to initiate the second random access, so as to ensure the normal switching of these terminals.

[0201] From the perspective of the second DU, the second DU can allocate a third random access resource for the first random access and the second random access, that is, the second DU may not distinguish between the first random access and the second random access when allocating random access resources; whether the third random access resource is specifically used for the first random access or the second random access can be flexibly determined by the first DU (source DU) and indicated to the second DU, and then the second DU can determine the random access corresponding to the random access request according to the indication of the first DU, so as to ensure the normal switching of the terminal.

[0202] With respect to the above embodiments, it can be understood that:

[0203] (1) The above description focuses on the differences between the first embodiment and the second embodiment. Except for the differences, the two embodiments can refer to each other.

[0204] (2) The step numbers of the flowcharts described in the above embodiments are only examples of the execution process and do not constitute a limitation on the order of execution of the steps. There is no strict execution order between the steps that have no temporal dependency relationship with each other in the embodiments of the present application. Not all the steps shown in the flowcharts are steps that must be executed. Some steps can be deleted based on each flowchart according to actual needs, or other possible steps can be added based on each flowchart according to actual needs.

[0205] (3) The message name used in the above embodiment is only an example, and the embodiment of the present application does not limit the message name. The above is described using inter-DU switching as an example, and the solution in the embodiment of the present application can also be extended to other scenarios. For example, it can be extended to intra-DU (that is, the first DU and the second DU are the same DU). In this case, the communication between the first DU and the second DU may not be involved. For another example, it can be extended to the inter-gNB scenario (that is, the first DU and CU belong to one gNB, and the second DU belongs to another gNB). In this case, the above UE context establishment request message can be replaced with a switching request message, and the UE context establishment response message can be replaced with a switching response message.

[0206] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of the interaction between the terminal and the network device. It is understandable that in order to achieve the above functions, the terminal and the network device may include hardware structures and / or software modules corresponding to the execution of each function. It should be easily appreciated by those skilled in the art that, in combination with the units and algorithm steps of each example described in the embodiments disclosed herein, the embodiments of the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0207] The embodiment of the present application can divide the network device into functional units according to the above method example. For example, each functional unit can be divided according to each function, or two or more functions can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or software functional unit.

[0208] In the case of an integrated unit, Figure 7 A possible exemplary block diagram of the device involved in the embodiments of the present application is shown. Figure 7 As shown, the apparatus 700 may include: a processing unit 702 and a communication unit 703. The processing unit 702 is used to control and manage the actions of the apparatus 700. The communication unit 703 is used to support the communication between the apparatus 700 and other devices. Optionally, the communication unit 703 is also called a transceiver unit, and may include a receiving unit and / or a sending unit, which are respectively used to perform receiving and sending operations. The apparatus 700 may also include a storage unit 701, which is used to store program codes and / or data of the apparatus 700.

[0209] (1) The apparatus 700 may be the third network device (e.g., the second DU) in the above embodiment. The processing unit 702 may support the apparatus 700 in executing the actions of the second DU in each method example above. Alternatively, the processing unit 702 mainly executes the internal actions of the second DU in the method example, and the communication unit 703 may support the communication between the apparatus 700 and other devices.

[0210] For example, in one embodiment, the communication unit 703 is used to: receive a random access request from a first terminal on a first cell; the processing unit 702 is used to: determine whether the random access request corresponds to a first random access or a second random access; the communication unit 703 is also used to: when the random access request corresponds to a first random access, send a timing advance TA of the first cell to a first network device; when the random access request corresponds to a second random access, send the TA to the first terminal; wherein the first random access is a random access before switching, and the second random access is a random access after switching.

[0211] In one possible design, the processing unit 702 is specifically used to: if the random access resource corresponding to the random access request is a first random access resource, determine that the random access request corresponds to the first random access; if the random access resource corresponding to the random access request is a second random access resource, determine that the random access request corresponds to the second random access.

[0212] In a possible design, the communication unit 703 is further used to: send a first message to the first network device, where the first message is used to indicate that the first random access resource corresponds to the first random access and the second random access resource corresponds to the second random access.

[0213] In a possible design, the communication unit 703 is also used to: receive a first request message from the first network device, where the first request message is used to request allocation of random access resources corresponding to the first random access and / or random access resources corresponding to the second random access.

[0214] In a possible design, the communication unit 703 is further used to: receive first indication information from a second network device; and determine, based on the first indication information, whether the random access request corresponds to the first random access or the second random access.

[0215] In one possible design, the random access request corresponds to a third random access resource; the processing unit 702 is specifically used to: if the first indication information indicates that the third random access resource corresponds to the first random access, determine that the random access request corresponds to the first random access; if the first indication information indicates that the third random access resource corresponds to the second random access, determine that the random access request corresponds to the second random access.

[0216] In a possible design, the communication unit 703 is further used to: send a second message to the first network device, where the second message is used to indicate that the third random access resource corresponds to the first random access and the second random access.

[0217] In a possible design, the communication unit 703 is further used to: receive a second request message from the first network device, where the second request message is used to request allocation of random access resources corresponding to the first random access and the second random access.

[0218] In one possible design, the communication unit 703 is also used to: receive second indication information from a second network device, where the second indication information is used to indicate beam information of the first cell; and send a random access response to the first terminal according to the beam information, where the random access response includes the TA.

[0219] (2) The device 700 may be the second network device (e.g., the first DU) in the above embodiment. The processing unit 702 may support the device 700 in executing the actions of the first DU in each method example above. Alternatively, the processing unit 702 mainly executes the internal actions of the first DU in the method example, and the communication unit 703 may support the communication between the device 700 and other devices.

[0220] For example, in one embodiment, the communication unit 703 is used to: receive a third message from the first network device, the third message being used to indicate that the first random access resource corresponds to the first random access and the second random access resource corresponds to the second random access; the processing unit 702 is used to: determine that the first terminal needs to initiate the first random access or the second random access; the communication unit 703 is also used to: when the first terminal needs to initiate the first random access, send third indication information to the first terminal, the third indication information being used to instruct the first terminal to use the first random access resource to send a first random access request on the first cell; when the first terminal needs to initiate the second random access, send fourth indication information to the first terminal, the fourth indication information being used to instruct the first terminal to use the second random access resource to send a second random access request on the first cell; wherein the first random access is a random access before switching, and the second random access is a random access after switching.

[0221] In one possible design, if it is determined that the first terminal needs to initiate the first random access, the communication unit 703 is also used to: receive the TA of the first cell from the third network device; send a switching command to the first terminal, the switching command is used to indicate that the first cell is the target cell, and the switching command includes the TA.

[0222] In one possible design, if it is determined that the first terminal needs to initiate the second random access, the communication unit 703 is also used to: send second indication information to a third network device, the second indication information is used to indicate the beam information of the first cell, and the beam information is used by the third network device to send the TA of the first cell to the first terminal.

[0223] In one possible design, if it is determined that the first terminal needs to initiate the second random access, the communication unit 703 is also used to: send fifth indication information to the first terminal, the fifth indication information is used to indicate the beam information of the first cell, and the beam information is used by the first terminal to receive the TA of the first cell.

[0224] (3) The device 700 may be the second network device (e.g., the first DU) in the above embodiment. The processing unit 702 may support the device 700 in executing the actions of the first DU in each method example above. Alternatively, the processing unit 702 mainly executes the internal actions of the first DU in the method example, and the communication unit 703 may support the communication between the device 700 and other devices.

[0225] For example, in one embodiment, the communication unit 703 is used to: receive a fourth message from the second network device, the fourth message being used to indicate that the third random access resource corresponds to the first random access and the second random access; the processing unit 702 is used to: determine that the first terminal needs to initiate the first random access or the second random access; the communication unit 703 is also used to: when the first terminal needs to initiate the first random access, send third indication information to the first terminal, the third indication information being used to instruct the first terminal to use the third random access resource to send a first random access request on the first cell; when the first terminal needs to initiate the second random access, send fourth indication information to the first terminal, the fourth indication information being used to instruct the first terminal to use the third random access resource to send a second random access request on the first cell; wherein the first random access is a random access before switching, and the second random access is a random access after switching.

[0226] In one possible design, if it is determined that the first terminal needs to initiate the first random access, the communication unit 703 is also used to: receive the TA of the first cell from the third network device; send a switching command to the first terminal, the switching command is used to indicate that the first cell is the target cell, and the switching command includes the TA.

[0227] In one possible design, if it is determined that the first terminal needs to initiate the second random access, the communication unit 703 is also used to: send second indication information to a third network device, the second indication information is used to indicate the beam information of the first cell, and the beam information is used by the third network device to send the TA of the first cell to the first terminal.

[0228] In one possible design, if it is determined that the first terminal needs to initiate the second random access, the communication unit 703 is also used to: send fifth indication information to the first terminal, the fifth indication information is used to indicate the beam information of the first cell, and the beam information is used by the first terminal to receive the TA of the first cell.

[0229] It should be understood that the division of the units in the above device is only a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. And the units in the device can all be implemented in the form of software calling through processing elements; they can also be all implemented in the form of hardware; some units can also be implemented in the form of software calling through processing elements, and some units can be implemented in the form of hardware. For example, each unit can be a separately established processing element, or it can be integrated in a certain chip of the device. In addition, it can also be stored in the memory in the form of a program, and called and executed by a certain processing element of the device. The function of the unit. In addition, all or part of these units can be integrated together, or they can be implemented independently. The processing element described here can also be a processor, which can be an integrated circuit with signal processing capabilities. In the implementation process, each operation of the above method or each unit above can be implemented by an integrated logic circuit of hardware in the processor element or in the form of software calling through a processing element.

[0230] In one example, the unit in any of the above devices may be one or more integrated circuits configured to implement the above method, such as one or more application specific integrated circuits (ASIC), or one or more digital singnal processors (DSP), or one or more field programmable gate arrays (FPGA), or a combination of at least two of these integrated circuit forms. For another example, when the unit in the device can be implemented in the form of a processing element scheduler, the processing element can be a processor, such as a general-purpose central processing unit (CPU), or other processors that can call programs. For another example, these units can be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0231] The above unit for receiving is an interface circuit of the device, which is used to receive signals from other devices. For example, when the device is implemented in the form of a chip, the receiving unit is an interface circuit of the chip used to receive signals from other chips or devices. The above unit for sending is an interface circuit of the device, which is used to send signals to other devices. For example, when the device is implemented in the form of a chip, the sending unit is an interface circuit of the chip used to send signals to other chips or devices.

[0232] Based on the above embodiments, the present application also provides a communication device, referring to Figure 8As shown, the communication device 800 may include a transceiver 801 and a processor 802. Optionally, the communication device 800 may further include a memory 803. The memory 803 may be arranged inside the communication device 800 or outside the communication device 800. The processor 802 may control the transceiver 801 to receive and send messages, etc.

[0233] Specifically, the processor 802 may be a central processing unit (CPU), a network processor (NP) or a combination of a CPU and a NP. The processor 802 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD) or a combination thereof. The PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL) or any combination thereof.

[0234] The transceiver 801, the processor 802 and the memory 803 are interconnected. Optionally, the transceiver 801, the processor 802 and the memory 803 are interconnected via a bus 804; the bus 804 may be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 8 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0235] In an optional implementation, the memory 803 is used to store programs, etc. Specifically, the program may include a program code, and the program code includes a computer operation instruction. The memory 803 may include a RAM, and may also include a non-volatile memory (non-volatile memory), such as one or more disk memories. The processor 802 executes the application stored in the memory 803 to implement the above functions, thereby realizing the functions of the communication device 800.

[0236] Exemplarily, the communication device 800 may be the first DU in the above embodiment; or may be the second DU in the above embodiment.

[0237] In one embodiment, when the communication device 800 implements the function of the first DU in the above method embodiment, the transceiver 801 can implement the transceiver operation performed by the first DU in the above method embodiment; the processor 802 can implement other operations except the transceiver operation performed by the first DU in the above method embodiment. For specific related descriptions, please refer to the related descriptions in the above embodiments, which will not be described in detail here.

[0238] In another embodiment, when the communication device 800 implements the function of the second DU in the above method embodiment, the transceiver 801 can implement the transceiver operation performed by the second DU in the above method embodiment; the processor 802 can implement other operations except the transceiver operation performed by the second DU in the above method embodiment. For specific related descriptions, please refer to the related descriptions in the above embodiments, which will not be described in detail here.

[0239] The terms "system" and "network" in the embodiments of the present application can be used interchangeably. "At least one" refers to one or more, and "multiple" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B, which can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following (individuals)" or similar expressions thereof refer to any combination of these items, including any combination of single items (individuals) or plural items (individuals). For example, "at least one of A, B and C" includes A, B, C, AB, AC, BC or ABC. And, unless otherwise specified, the ordinal numbers such as "first" and "second" mentioned in the embodiments of the present application are used to distinguish multiple objects, and are not used to limit the order, timing, priority or importance of multiple objects.

[0240] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0241] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0242] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0243] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0244] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A communication method, characterized in that: The method comprises: Receiving a random access request from a first terminal on a first cell; Determining that the random access request corresponds to a first random access or a second random access; When the random access request corresponds to a first random access, sending a timing advance TA of the first cell to the first network device; When the random access request corresponds to a second random access, sending the TA to the first terminal; The first random access is a random access before switching, and the second random access is a random access after switching.

2. The method according to claim 1, characterized in that Determining that the random access request corresponds to a first random access or a second random access includes: If the random access resource corresponding to the random access request is a first random access resource, determining that the random access request corresponds to the first random access; If the random access resource corresponding to the random access request is a second random access resource, it is determined that the random access request corresponds to the second random access.

3. The method according to claim 2, characterized in that The method further comprises: A first message is sent to the first network device, where the first message is used to indicate that the first random access resource corresponds to the first random access and the second random access resource corresponds to the second random access.

4. The method according to claim 3, characterized in that: The method further comprises: A first request message is received from the first network device, where the first request message is used to request allocation of random access resources corresponding to the first random access and random access resources corresponding to the second random access.

5. The method according to any one of claims 2 to 4, characterized in that The first random access is a non-contention-based random access; The first random access resource is used for multiple terminals to perform the first random access, and source network devices of the multiple terminals are all second network devices.

6. The method according to any one of claims 2 to 5, characterized in that The second random access is a non-contention based random access; The second random access resource is used for multiple terminals to perform the second random access, and source network devices of the multiple terminals are all second network devices; or, the second random access resource is dedicated to the first terminal.

7. The method according to claim 1, characterized in that The method further comprises: Receiving first indication information from a second network device; It is determined, according to the first indication information, that the random access request corresponds to the first random access or the second random access.

8. The method according to claim 7, characterized in that The random access request corresponds to a third random access resource; Determining, according to the first indication information, that the random access request corresponds to the first random access or the second random access includes: If the first indication information indicates that the third random access resource corresponds to the first random access, determining that the random access request corresponds to the first random access; If the first indication information indicates that the third random access resource corresponds to the second random access, it is determined that the random access request corresponds to the second random access.

9. The method according to claim 7 or 8, characterized in that: The method further comprises: A second message is sent to the first network device, where the second message is used to indicate that the third random access resource corresponds to the first random access and the second random access.

10. The method according to claim 9, characterized in that The method further comprises: A second request message is received from the first network device, where the second request message is used to request allocation of random access resources corresponding to the first random access and the second random access.

11. The method according to any one of claims 7 to 10, characterized in that The first random access and the second random access are both non-contention-based random access; The third random access resource is used for multiple terminals to perform the first random access and the second random access, and source network devices of the multiple terminals are all second network devices.

12. The method according to any one of claims 1 to 11, characterized in that Sending the TA to the first terminal includes: receiving second indication information from a second network device, where the second indication information is used to indicate beam information of the first cell; Send a random access response to the first terminal according to the beam information, where the random access response includes the TA.

13. A communication method, characterized in that: The method comprises: receiving a third message from the first network device, where the third message is used to indicate that the first random access resource corresponds to a first random access and the second random access resource corresponds to a second random access; If it is determined that the first terminal needs to initiate the first random access, third indication information is sent to the first terminal, where the third indication information is used to instruct the first terminal to use the first random access resource to send a first random access request on the first cell; If it is determined that the first terminal needs to initiate the second random access, sending fourth indication information to the first terminal, where the fourth indication information is used to instruct the first terminal to use the second random access resource to send a second random access request on the first cell; The first random access is a random access before switching, and the second random access is a random access after switching.

14. The method according to claim 13, characterized in that The first random access is a non-contention-based random access; The first random access resource is used for multiple terminals to perform the first random access, and source network devices of the multiple terminals are all second network devices.

15. The method according to claim 13 or 14, characterized in that The second random access is a non-contention based random access; The second random access resource is used for multiple terminals to perform the second random access, and source network devices of the multiple terminals are all second network devices; or, the second random access resource is dedicated to the first terminal.

16. A communication method, characterized in that: The method comprises: receiving a fourth message from the second network device, where the fourth message is used to indicate that the third random access resource corresponds to the first random access and the second random access; If it is determined that the first terminal needs to initiate the first random access, third indication information is sent to the first terminal, where the third indication information is used to instruct the first terminal to use the third random access resource to send a first random access request on the first cell; If it is determined that the first terminal needs to initiate the second random access, sending fourth indication information to the first terminal, where the fourth indication information is used to instruct the first terminal to use the third random access resource to send a second random access request on the first cell; The first random access is a random access before switching, and the second random access is a random access after switching.

17. The method according to claim 16, characterized in that The first random access and the second random access are both non-contention-based random access; The third random access resource is used for multiple terminals to perform the first random access and the second random access, and source network devices of the multiple terminals are all second network devices.

18. The method according to claim 16 or 17, characterized in that The method further comprises: Sending first indication information to the third network device; Among them, if it is determined that the first terminal needs to initiate the first random access, the first indication information is used to indicate that the third random access resource corresponds to the first random access; if it is determined that the first terminal needs to initiate the second random access, the first indication information is used to indicate that the third random access resource corresponds to the second random access.

19. The method according to any one of claims 13 to 18, characterized in that If it is determined that the first terminal needs to initiate the first random access, the method further includes: receiving a TA of the first cell from a third network device; A handover command is sent to the first terminal, where the handover command is used to indicate that the first cell is a target cell, and the handover command includes the TA.

20. The method according to any one of claims 13 to 19, characterized in that If it is determined that the first terminal needs to initiate the second random access, the method further includes: Send second indication information to a third network device, where the second indication information is used to indicate beam information of the first cell, and the beam information is used by the third network device to send the TA of the first cell to the first terminal.

21. The method according to any one of claims 13 to 20, characterized in that If it is determined that the first terminal needs to initiate the second random access, the method further includes: Fifth indication information is sent to the first terminal, where the fifth indication information is used to indicate beam information of the first cell, and the beam information is used by the first terminal to receive the TA of the first cell.

22. A communication device, characterized in that: Comprising modules for executing the method as claimed in any one of claims 1 to 21.

23. A communication device, characterized in that: It includes a processor, which is coupled to a memory, and a computer program is stored in the memory; the processor is used to call the computer program in the memory so that the communication device executes any method as claimed in claims 1 to 21.

24. A communication system, characterized in that: The communication system comprises a first communication device and a second communication device; wherein the first communication device is used to execute the method described in any one of claims 1 to 12, and the second communication device is used to execute the method described in any one of claims 13 to 21.

25. A computer-readable storage medium, characterized in that: The storage medium stores a computer program or instruction, and when the computer program or instruction is executed by a computer, the method as claimed in any one of claims 1 to 21 is implemented.

26. A computer program product, characterized in that When a computer reads and executes the computer program product, the computer is enabled to execute the method according to any one of claims 1 to 21.

Images